Google+ became the fastest growing social network within months of its debut last June, but a recent study casts doubt on whether most of its users are spending much time on the site.

According to ComScore, users spent an average of just 3.3 minutes on Google+ in the month of January, a decline from its recent figures and a tiny sliver of Facebook’s total.

On average, users spent 5.1 minutes on Google+ in November and 4.8 minutes in December while Facebook’s passionate audience logged between six and seven hours each of the past few months.

Most of the prominent social media companies site fall well short of Facebook by this measurement, but still lure their users for far longer than Google+. That even includes MySpace, which has an audience that is 27 million visitors smaller than Google+’s, but one that spend almost three times as much time on it.

This study only accounts for visitors using personal computers, so mobile is usage is not considered. But Facebook also has a large and active audience on the mobile platform – albeit one it needs to better monetize.

A Google spokeswoman gave this statement on the report: "The reality that Google+ is much more than a destination site makes it exceedingly hard for any third-party research firm to monitor or measure its performance. Google thinks about the service not as a site but as a deepening of its relationship to billions of existing users who are already committed to Google's services like Search, YouTube, Android, etc. By this measure, engagement is already enormous."

Google CEO Larry Page has struck an optimistic tone ever since the Mountain View, Calif.-based company debuted its social networking platform. In its most recent earnings call, he boasted of its 90 million users.